1. Field of the Invention
The present invention relates to a heat transfer printing on an acidic modified synthetic fiber using an ink composition containing an indolenine methine compound to form a dye by quaternizing the indolenine methine compound with acidic groups of the acidic modified synthetic fiber.
2. Description of the Prior Art
The transfer printing techniques have been remarkably developed in these several years. Especially the transfer printing by sublimation of dyes has been developed because of the labour reduction in the dyeing process and the social requirement for preventing pollution. In the polyester fiber field, the transfer printing techniques have been employed at a ratio of 10 to 15%.
The reasons why the transfer printing techniques have been considered in the world-wide and have been applied in various fields, are to easily obtain printed textiles and to eliminate the soaping and water washing as the post-treatment for the dyeing process whereby the treatment of drainage which is the most important problem in a dyeing factory can be remarkably rationalized.
In the circumstance, the heat transfer printing on polyester fiber by using dispersing dyes has been employed in an industrial scale. However, the heat transfer printing on the acryl type fiber by using cationic dyes has not been practically employed because the cationic dyes have low sublimation transfer printability and the fastness of the textile dyed by the sublimation transfer printability is inferior to that of the textile dyed by the conventional process.
However, various techniques for applications on acryl type fiber have been proposed. For example, in order to improve the transfer printability of cation dyes, it has been proposed to provide a transfer printing under a reduced pressure and a transfer printing of free base type dyes. However, in the former method, the apparatus and the dyes are substantially limited. On the other hand, in the latter method, the free base type dyes are instable to be difficult for blending the dyes in the ink composition for transfer printing and the stability of the transfer printing paper prepared with such ink composition containing the free base type dye is not satisfactory.